The Darién Region, Connecting Road of the Americas, among the expressions of hydric wealth, land vocation and the extractive exploration on its violated forms

Colombia has oceanic waters, catchment areas, like lakes, cienagas and swamps, water flows, like rivers, gorges and streams, small rivers and groundwater. The oceanic waters are the Caribbean Sea-1600 km and the Pacific Ocean-1300 km that comprise the north and west continental territory, respectively. Actually the Region of Darién, geographically bounded by the Carribean Sea to the north is becoming to be focused by studies due to use conflicts and disputes about water and a forest reserve on its territories. Considering its location, strategic at northwestern Colombia, frontier region with Central America, several dynamics are imposed. One of them is the implantation of a road system entitled Connecting Road of the Americas. This fact means the construction of an infra-structure that will cross a special zone formed by swamps and jungle known as The Darién Gap. Evidences of such interests are revealed by projects like the constructions of Turbo's Port in the Atlantic Ocean, Department of Antioquia and Tribugá's Port in the Pacific Ocean, Department of Choco, the mountain road and the coastal conection Colombia-Venezuela attending to the main intentions of the central region of the department (Metropolitan Area of Aburrá Valley-AMVA). Human settlements form a productive system, based on small and medium familiar agriculture's production, corresponding to the western portion and piedmont of Abibe's mountain at its antioquian portion, alluvial plan that forms the rivers on this area, the littoral zone that delimits the Carribean Sea, the Darién and Baudó Mountains and the gulf that receives, among other waters, the ones from Atrato and León, as well as the exodus process constitutes a forced exit resulting from actions of several armed groups. It can be identified intense historical, cultural, political and environmental relations, specially the last one associated with strategic ecosystems that are fundamental for the hydric regulation of the region, as well as food safety of the local inhabitants. Results from two researches (UPB, 2007 y 2010) reveals this quick transformation in the spatial re-configuration, demographical and economical indicators and the exacerbated fight for resources, damaging the extractive vocation in the Region. Path to commerce of illegalities (drugs, guns) and to implementation of the agroindustrial project for biofuel production, cooperation program that involves Venezuela, Brazil and Colombia. Appropriation modes allow the existence of strategies since global interests revealing a development logic that privileges the conception of an artificialized nature. Since the smallest portion of rural areas, specific modes of resources exploration are linked to imposed interests of transnational corporations. Disparate consequences are going deeper evidenced by social, technical and nature transformations, envisioning risks for the habitability's condition

Calcite saturation and yield and Mg/Ca, Mn/Ca, Al/Ca, Fe/Ca for four species of planktic foraminifera cleaned using Mg-cleaning and Cd-cleaning methods

Four species of planktic foraminifera from core-tops spanning a depth transect on the Ontong Java Plateau were prepared for Mg/Ca analysis both with (Cd-cleaning) and without (Mg-cleaning) a reductive cleaning step. Reductive cleaning caused etching of foraminiferal calcite, focused on Mg-rich inner calcite, even on tests which had already been partially dissolved at the seafloor. Despite corrosion, there was no difference in Mg/Ca of Pulleniatina obliquiloculata between cleaning methods. Reductive cleaning decreased Mg/Ca by an average (all depths) of ~ 4% for Globigerinoides ruber white and ~ 10% for Neogloboquadrina dutertrei. Mg/Ca of Globigerinoides sacculifer (above the calcite saturation horizon only) was 5% lower after reductive cleaning. The decrease in Mg/Ca due to reductive cleaning appeared insensitive to preservation state for G. ruber, N. dutertrei and P. obliquiloculata. Mg/Ca of Cd-cleaned G. sacculifer appeared less sensitive to dissolution than that of Mg-cleaned. Mg-cleaning is adequate, but SEM and contaminants (Al/Ca, Fe/Ca and Mn/Ca) show that Cd-cleaning is more effective for porous species. A second aspect of the study addressed sample loss during cleaning. Lower yield after Cd-cleaning for G. ruber, G. sacculifer and N. dutertrei confirmed this to be the more aggressive method. Strongest correlations between yield and Delta[CO3^2-] in core-top samples were for Cd-cleaned G. ruber (r = 0.88, p = 0.020) and Cd-cleaned P. obliquiloculata (r = 0.68, p = 0.030). In a down-core record (WIND28K) correlation, r, between yield values > 30% and dissolution index, XDX, was -0.61 (p = 0.002). Where cleaning yield < 30% most Mg-cleaned Mg/Ca values were biased by dissolution.

Carbon/oxygen ratios, clay composition and gas-hydrate saturation of ODP Leg 164 sites

The analyses of downhole log data from Ocean Drilling Program (ODP) boreholes on the Blake Ridge at Sites 994, 995, and 997 indicate that the Schlumberger geochemical logging tool (GLT) may yield useful gas hydrate reservoir data. In neutron spectroscopy downhole logging, each element has a characteristic gamma ray that is emitted from a given neutron-element interaction. Specific elements can be identified by their characteristic gamma-ray signature, with the intensity of emission related to the atomic elemental concentration. By combining elemental yields from neutron spectroscopy logs, reservoir parameters including porosities, lithologies, formation fluid salinities, and hydrocarbon saturations (including gas hydrate) can be calculated. Carbon and oxygen elemental data from the GLT was used to determine gas hydrate saturations at all three sites (Sites 994, 995, and 997) drilled on the Blake Ridge during Leg 164. Detailed analyses of the carbon and oxygen content of various sediments and formation fluids were used to construct specialized carbon/oxygen ratio (COR) fan charts for a series of hypothetical gas hydrate accumulations. For more complex geologic systems, a modified version of the standard three-component COR hydrocarbon saturation equation was developed and used to calculate gas hydrate saturations on the Blake Ridge. The COR-calculated gas hydrate saturations (ranging from about 2% to 14% bulk volume gas hydrate) from the Blake Ridge compare favorably to the gas hydrate saturations derived from electrical resistivity log measurements.

Hysteresis between coral reef calcification and the seawater aragonite saturation state

Some predictions of how ocean acidification (OA) will affect coral reefs assume a linear functional relationship between the ambient seawater aragonite saturation state (Omega a) and net ecosystem calcification (NEC). We quantified NEC in a healthy coral reef lagoon in the Great Barrier Reef during different times of the day. Our observations revealed a diel hysteresis pattern in the NEC versus Omega a relationship, with peak NEC rates occurring before the Omega a peak and relatively steady nighttime NEC in spite of variable Omega a. Net ecosystem production had stronger correlations with NEC than light, temperature, nutrients, pH, and Omega a. The observed hysteresis may represent an overlooked challenge for predicting the effects of OA on coral reefs. If widespread, the hysteresis could prevent the use of a linear extrapolation to determine critical Omega a threshold levels required to shift coral reefs from a net calcifying to a net dissolving state.

Predominance of heavily calcified coccolithophores at low CaCO3 saturation during winter in the Bay of Biscay

Coccolithophores are an important component of the Earth system, and, as calcifiers, their possible susceptibility to ocean acidification is of major concern. Laboratory studies at enhanced pCO2 levels have produced divergent results without overall consensus. However, it has been predicted from these studies that, although calcification may not be depressed in all species, acidification will produce "a transition in dominance from more to less heavily calcified coccolithophores" [Ridgwell A, et al., (2009) Biogeosciences 6:2611-2623]. A recent observational study [Beaufort L, et al., (2011) Nature 476:80-83] also suggested that coccolithophores are less calcified in more acidic conditions. We present the results of a large observational study of coccolithophore morphology in the Bay of Biscay. Samples were collected once a month for over a year, along a 1,000-km-long transect. Our data clearly show that there is a pronounced seasonality in the morphotypes of Emiliania huxleyi, the most abundant coccolithophore species. Whereas pH and CaCO3 saturation are lowest in winter, the E. huxleyi population shifts from <10% (summer) to >90% (winter) of the heavily calcified form. However, it is unlikely that the shifts in carbonate chemistry alone caused the morphotype shift. Our finding that the most heavily calcified morphotype dominates when conditions are most acidic is contrary to the earlier predictions and raises further questions about the fate of coccolithophores in a high-CO2 world.

The influence of temperature and seawater carbonate saturation state on 13C-18O bond ordering in bivalve mollusks

The shells of marine mollusks are widely used archives of past climate and ocean chemistry. Whilst the measurement of mollusk delta 18O to develop records of past climate change is a commonly used approach, it has proven challenging to develop reliable independent paleothermometers that can be used to deconvolve the contributions of temperature and fluid composition on molluscan oxygen isotope compositions. Here we investigate the temperature dependence of 13C-18O bond abundance, denoted by the measured parameter Delta 47, in shell carbonates of bivalve mollusks and assess its potential to be a useful paleothermometer. We report measurements on cultured specimens spanning a range in water temperatures of 5 to 25 °C, and field collected specimens spanning a range of -1 to 29 °C. In addition we investigate the potential influence of carbonate saturation state on bivalve stable isotope compositions by making measurements on both calcitic and aragonitic specimens that have been cultured in seawater that is either supersaturated or undersaturated with respect to aragonite. We find a robust relationship between Delta 47 and growth temperature. We also find that the slope of a linear regression through all the Delta 47 data for bivalves plotted against seawater temperature is significantly shallower than previously published inorganic and biogenic carbonate calibration studies produced in our laboratory and go on to discuss the possible sources of this difference. We find that changing seawater saturation state does not have significant effect on the Delta 47 of bivalve shell carbonate in two taxa that we examined, and we do not observe significant differences between Delta 47-temperature relationships between calcitic and aragonitic taxa.